Of the two links you posted, it was definitely sand fleas.
We were also there on Jan. 29th and they were VERY bad. My wife really got bit up around her ankles and is still experiencing swelling and itching as I type this. She has been taking Benadryl which really seems to help alot and she can tell when the medicine is starting to wear off.
We first noticed the bugs when stopping along the walkway by the Flying Dutchmen to take pictures. Couldn't figure out why we got so itchy all of a sudden. The place I noticed them the worst was at the bike rental area. They were horrendous there and the poor lady sitting in the bike rental shack was going nuts trying to keep them off of her. We had chairs on the family beach in the first row right in front of the platform which is in the water. They would be all over the whitel towels and shirts but for some reason they did not seem to bite down on the beach even if they were on you. Still haven't figured that one out.
I think the problem with the bugs may have been more weather related than anything. It was very nice when we were there with sun, warm temps and a very light (almost nonexistent) breeze. I think it is generally much more breezy on the island and I bet that really keeps these bugs down when the wind is more normal.
As far as constuction goes, it was pretty noticeable but I don't think it should really bother anyone as everybody knows what is going on. There was a Lull forklift running around by the pier. On the walkway from the pier to the shops there was an excavator in plain site which was cleaning out the bottom of a lagoon. I probably noticed the construction most at the bike rental area. The area is completely surrounded by construction fencing which is kind of a see through green mesh so you can still see what is happening. At the rental hut the bike helmets were up against a fence and only about 20 feet behind that they fence they are constructing a small building. When I was there, they were using a crane to put in place some of the roof beams. They were trying to put a beam in place and the crane operator was not doing what the crew wanted him to do and there was a few swear words being thrown out. Finally, the crane operator ended up knocking down about 3 other beams which had aleady been put up and it was kind of a dangerours situation there for the construction workers for a few seconds as beams were toppling to the ground and the workers were getting out of the way. The crane operator shut the engine down and the crew spent the next few minutes arguing with each other about who was wrong and basically cussing each other out the whole time. Lots of swear words flying around at that time including the F word. I think I got to hear what every single swear word sounds like with a Bahamian accent. I really just found it all sort of amusing but I'm sure there are some people who would make a big deal about it and complain.
I think what I'm trying to say is that there WILL be construction taking place when you are there. I had read references on here before that they would not be working when guests are on the island and that is definitely not true. There were dozens of construction workers hard at work throughout the day.
I'm getting all itchy too. I hope it's breezy the week of May 9th when I'm there 
